Method and apparatus for forming and attaching filament support members



Sept. 6, 1966 w. L. BRUNDIGE 3,270,731

METHOD AND APPARATUS FOR FORMING AND ATTACHING FILAMENT SUPPORT MEMBERS 2 Sheets-Sheet 1 Filed May 17, 1963 FIG. 1.

FIG. 3.

INVENTOR.

WILLIAM L. BR UNDIGE.

FIG.6.

Sept. 6, 1966 w. L.

METHOD AND APPARATUS Filed May 17, 1963 FILAMENT SUPPORT MEMBE BRUNDIGE FOR FORMING AND ATTACHING RS 2 Sheets-Sheet 2 INVENTOR.

WILLIAM L. BRUNDiGE United States Patent METHOD AND APPARATUS FOR FORMING AND ATTACHING FHLAMENT SUPPORT MEMBERS William L. Brundige, West Caldwell, N..I., assignor to Westinghouse Electric Corporation, Pittsburgh, Pa., a

corporation of Pennsylvania Filed May 17, 1%3, Ser. No. 281,293 8 Claims. '(Cl. 14071.5)

This invention relates to electric lamps and has particular reference to an improved method and apparatus for simultaneously forming a wire support member and mounting it on a coiled filament.

The production problems and bottle-necks which this invention alleviates originated with a new class of radiation generating devices, commonly referred to as T3 quartz iodine lamps, now being marketed. As presently manufactured, such lamps comprise a linear coiled filament of relatively heavy tungsten wire that is sealed within and coaxially supported within a tubular quartz envelope approximately /8 of an inch in diameter. These lamps are very compact and are made in various wattage ratings. Their spectral emission is such that they can be used either as light or heat sources.

In order to obtain maximum life and efficiency a small amount of iodine is added to the inert gas fill. Due to the high operating temperatures which prevail during use, a tungsten-iodine cycle is established within the lamp which redeposits vaporized tungsten on the filament and thus prevents the bulb blackening and drop in light output that would otherwise occur. Since iodine vapor is very corrosive, the filament supports for such lamps must be made from tungsten instead of tantalum or other material which reacts with iodine. The supports are customarily made from tungsten wire that is formed into a loop of the proper size and attached to the filament.

Heretofore, these tungsten wire support members have either been pre-formed and manually attached to the filament by crimping an inturned end of the support around the filament, or they have been laboriously formed by hand from straight pieces of tungsten wire and attached to the filament as part of the mount assembly operation. Another approach has been to form the tungsten wire into a stepped spiral or helix that tapers down to coiled end section dimensioned to threadably engage the turns of the filament. These pre-formed supports are then threaded onto the filament until properly positioned and are then anchored in place by crimping the coiled end section.

It is accordingly the general object of the present invention to provide an improved method of manufacturing a wire support member for incandescible filaments that will avoid the foregoing and other problems of the prior art.

A more specific object of the invention is to provide a method for simultaneously forming a support member from resilient relatively stilf wire and attaching it to a coiled lamp filament quickly and efficiently.

A further object is the provision of a reliable inexpensive apparatus for performing the simultaneous forming and mounting operations of the aforesaid method.

The foregoing objects and other attendant advantages are achieved in accordance with the present invention by positioning a straight piece of tungsten wire in tangential contacting relationship with the coiled filament and 3,270,781 Patented Sept. 6, 1966 tightly winding one end of the wire around the filament while simultaneously bending the other end of the wire into an arcuate loop or helix of the proper configuration and size. The portion of the wire wrapped around the filament is wound first in one direction and then in the opposite direction to form overlying cross-threaded turns that mechanically lock the support in its mounted position on the filament. The excess portions of wire protruding beyond the resulting support member are then removed to complete the assembly. Since the forming and fastening operations are performed simultaneously, the supports are fabricated and assembled on the filament at a much faster rate than heretofore and at reduced cost.

A preferred apparatus for fabricating and mounting wire supports in the aforesaid manner using a continuous supply of wire and a specially shaped mandrel is also disclosed.

A better understanding of the invention will be obtained by referring to the accompanying drawings, wherein:

FIGURE 1 is a fragmentary elevational view of an iodine-containing T3 quartz lamp having wire support members made in accordance with the present invention;

FIG. 2 is a front elevational view, partly in section, of one form of apparatus for forming and mounting the aforesaid wire supports on the filament;

FIG. 3 is a cross-sectional view along the line IIIIII of FIG. 1 illustrating the first step in fabricating the Support member utilizing a spooled wire supply;

FIG. 4 is an enlarged perspective view of the eccentric mandrel located at the end of the rotatable die member employed in the apparatus shown in FIGS. 2 and 3;

FIGS. 5 and 6 are enlarged side and plan views, respectively, of the Wire guiding and forming portions of the apparatus shown in the preceding figures;

FIGS. 7 to 14 are similar paired views illustrating subsequent phases in the fabrication of the wire support; and

FIG. 15 is an enlarged perspective view of the completed support member and the associated portion of the coiled filament.

While the present invention can be used with advantage in fabricating and attaching wire support members to various types of incandescible elements, it is especially suited for use in forming and mounting helical supports on elongated coiled filaments of the type used in T3 quartz lamps and has accordingly been so illustrated and will be so described.

With specific reference now to the drawings, in FIG. 1 there is shown a so-called T3 incandescent lamp 10 which generally comprises a tubular envelope 12 of quartz or similar heat-resistant light-transmitting material having an elongated coiled tungsten filament 14 sealed therein. The filament is attached to lead-in conductor assemblies 16 embedded in press seals 18 located at each end of the envelope. The filament 14 is maintained in a centrally located position within the envelope by the aforesaid assemblies and a series of tungsten wire auxiliary support members 20 fabricated in accordance with the principles of the present invention, which members will now be described.

Support member-construction As is shown in FIG. 15, the tungsten wire support members 20 are fabricated from a single piece of wire one end of which is mechanically locked to the coiled filament 14 by a plurality of inner turns 21 that are O1 wound tightly around the filament and held in this position by a plurality of outer overlying turns 22. The outer turns 22 are wound at a reverse pitch angle relative to the inner turns 21 and thus form what can be termed cross-wound or cross-threaded superposed turn groupings. These turns are integral with a laterally extending arm or spoke 24 that comprises the intermediate portion of the support and holds the enlarged helical body portion 26 formed from the other end of the wire in predetermined spaced and encircling relationship with the coiled filament 14. The diameter of the support 20 is slightly less than the inner diameter of the envelope -12.

In contrast to the prior art supports of this type, the body portion 26 of the support member 20 comprises a circular loop or helix that consists of a single turn and is supported in spaced coaxial relationship with the filament by a substantially straight spoke 24 which extends radially outward from and is tangent to the filament, as shown in FIG. 15. In addition, the final turn of the outer group of turns 22 is terminated by a short substantially straight segment or pigtail 25 that protrudes radially from the filament 14 in substantially the opposite direction as that of the spoke 24. This peculiar and unique configuration and orientation of the aforesaid elements results from the manner in which the support 20 is formed, as will be seen when this operation is described hereafter.

While the enlarged arcuate body portion 26 of the support member 20 is here shown as constituting a circular coaxial helix, it will be obvious that it can be bent into any suitable shape and, if a tubular envelope is involved as in the present case, it would still serve its intended filament-spacing function even though it comprises only a fraction of a turn.

Apparatus In FIGS. 2 and 3 there is shown one form of apparatus 28 for simultaneously forming and anchoring the tungsten wire support member 20 to the filament 14 in accordance with the invention. This apparatus consists generally of a base 30 having two uprights 31 and 32 spaced a predetermined distance apart. A pair of chucks 33 and 34 are attached to the upper ends of the uprights and are disposed toward one another along a predetermined axis. A rigid support rod 36 is releasably clamped in the chucks 33, 34 and is of such diameter that the coiled filament 14 can be loosely threaded thereover and shifted a predetermined distance d along the rod, as indicated by the arrow.

A standard 38 mounted on the base 30 between the chucks 33, 34 intersects the axis joining the chucks and supports an elongated die member 42 having a generally cylindrical mandrel 46 at one end. The die member and mandrel are rotatable within the standard on bearings 43, 44 mounted on the upper end thereof. The die member 42 'has a bore or aperture 45 that also extends through the mandrel 46 and is coincident with the axis joining the chucks 33, 34. This aperture is of such diameter that it freely receives a filament 14 supported by the rod 36, as illustrated in FIG. 2.

In the enlarged view of the mandrel 46 shown in FIG. 4, it will be noted that the mandrel is terminated by a substantially flat end face 47 and that the mandrel is eccentric with respect to the aperture 45 and, thus, the axis of the die member 42. The end face 47 is also provided with a re-entrant groove or slot 48 that extends from the periphery of the mandrel to the aperture 45 along a line that is tangent to the latter. The slot is also tapered toward the aperture 45 and extends from a point on the periphery of the mandrel that is furthest removed from the aperture. A portion of the end wall 47 overhangs the slot 48 and constitutes a protruding cleat or tooth 49.

Turning now to FIG. 3, a gear 40 is attached to the die member 42 and positioned so that it is engageable by another gear 53 carried by a drive shaft 54 that is also supported by the standard 38 and free to rotate therewithin on a bearing 55. As shown in FIG. 2, the other end of the drive shaft 54 is rotatably supported by the upright 32 and is provided with a handle 56 which, when rotated, causes the gear train to rotate the die member 42 around the support rod 36 and filament 114 placed thereon.

An upstanding guide member 50 is attached to the standard 38 by a mounting block 51 in such a position that the upper end of the member is located in line with the mandrel 46 and between the latter and the drive shaft 54. Another upright 57 is fastened to the base 30 at a point rearwardly of and in line with the standard 38 so that a spool 58 rotatably fastened to the upright by means of a bolt 60 is aligned with the end of aforementioned guide member 50 and mandrel 46. The spool 58 is disposed in a plane that is normal to the axis of the mandrel and, thus, to the coincident axis that joins the chucks 33, 34.

As shown in FIGS. 3 and 5, the size and location of the spool 58 are such that when the end of a supply of wire W stored on the spool is threaded through an aperture 52 in the upper end of the guide member 5%) and pulled taut by a pair of pliers 62 or the like so as to be substantially straight, the pulled-out section of wire will abut against the end face 47 of the mandrel 46 and lie tangent to the aperture 45 therein. By virtue of the foregoing, the end of the wire W can be guided along a path or axis that is transverse to the axis joining the chucks 33, 34 and tangent to the surface of a coiled filament 14 disposed on the support rod 36. The spool 58 is frictionally held by the bolt 60 so that when the end of the wire W is pulled downwardly along the aforesaid path, the unspooled length of wire is under sufficient tension to be straightened.

Operation The first step in fabricating the wire support member 20 is shown in FIGS. 3, 5 and 6 and consists of turning the drive shaft 54 until the slot 48 in the end of the mandrel 46 is aligned with the downwardly tilted aperture 52 in the guide member 50. The end of the wire W from the spool 58 is then threaded through the aperture 52 and slot 48 and over the filament 14 loaded onto the support rod 36. The wire W is then pulled along the transverse axis defined by the outer surface of the filament 14, the slot 48 and aperture 52 until a predetermined length of wire is pulled past the filament 14, as shown in FIG. 3. The filament 14 thus contacts an intermediate portion of the unspooled length of wire W at a point closer to the free end thereof than to the wire spool 58.

The drive shaft 54 is then rotated by means of the handle 56 in a direction such that the die member 42 and mandrel 46 rotate in a clockwise direction, as viewed in FIG. 7 and as indicated by the arrow. This causes the intermediate portion of the wire W seated in the slot 48 to be caught by and engage the protruding tooth 49. As a result, the portion of the wire immediately adacent the filament I4 and located on the spool side thereof is seated within the slot 48 and then bent around.

the outer surface of the mandrel 46 as shown in FIGS. 7 and 8. Simultaneously, the corresponding portion of the unspooled length of wire W located on the opposite side of the filament 14 is tightly wrapped around the filament by virtue of the fact that the free end of the wire is pulled downwardly and maintained under tension. The wire segment in the slot 48 thus remains straight and forms the spoke portion 24 of the support member, as indicated in FIG. 7.

Rotation of the mandrel 46 is continued and after approximately 1 /2 revolutions a corresponding number of large diameter turns 26' are wound around the face of the mandrel and the same number of small diameter turns 21 are wound around the filament I4, as shown in FIGS. 9 and 10. Attention is called to the fact that during this portion of the forming operation the end of the wire W is held so that it is displaced or skewed at a slight angle away from the end face 47 of the mandrel 46, as shown in FIG. 10. Thus, the larger turns 26' are wound about the mandrel 46 in one direction which the smaller turns 21 are tightly wound around the filament 14 in the opposite direction and the pitch angle of the smaller turns is initially the same as that of the filament turns. The diameter of the wire W is desirably slightly larger than the spacing between turns of the filament 14 so that the small diameter turns threadably interlock with the filament turns, as shown in FIG. 10. However, even if the wire were of smaller diameter than the spacing between turns of the filament the small turns 21 would seat against the support rod 36 and be secure'ly wedged between the filament turns and clamped in place.

After the mandrel 46 has rotated approximately 1 /2 times the angle of pull on the free end of the wire W is changed so that the wire is skewed toward the end face 47, as shown in FIG. 12. Rotation of the mandrel in a clockwise direction is continued for approximately an additional 1 /2 turns. As a result, a total of approximately three large diameter turns 26' are formed on the mandrel 46 and an additional 1 /2 small diameter turns 22 are cross-wound over the original 1 /2 small diameter turns 21 at a reverse pitch angle thereby mechanically locking the inner group of turns 21 in frictional engagement with the filament 14, as shown in FIGS. 11 and 12.

At this point rotation of the mandrel 46 is stopped and the wire W is cut by a pair of knives 64 at a point located between the mandrel and the guide member 50, I as shown in FIG. 12. Due to the natural resilience of the tungsten wire W, as soon as the wire is cut and the tension is relieved the large diameter turns 26' immediately spring away from the mandrel 46 and in a direction opposite to that in which they were wound. As a result, the initially formed turns 26' are converted into approximately 1 /2 turns 26 that are larger by a predetermined amount and disposed in substantially coaxial relationship with the filament 14, as shown in FIGS. 13 and 14. The opposite end of the Wire W is released right after the wire is cut.

At this stage of fabrication a substantially straight end segment 23 of wire projects tangentially from the final turn 22 in the outer group of small diameter turns and an arcuate and segment or tai-l 27 protrudes downwardly from the final turn 26, as shown in FIGS. 13 and 14. These excess end sections of the unspooled length of wire W are then severed at the points indicated in FIG. 14, thereby completing the operation and forming the wire support member 20 shown in FIG. 15. A sufficient amount of wire is trimmed from the ends of the support 20 so that the body portion 26 comprises substantially a single-turn helix and only a short pigtail 25 protrudes tangentially from the small-diametered turns 22 in a direction substantially opposite to that of the radially-extending spoke 24. The diameter and eccentricity of the mandrel 46 are such that the singleturn helix 26 is coaxial with the filament 14 and the support 20 nests within the tubular envelope 12.

Upon completion of the support member 20 the filament 14 is shifted a predetermined distance d along the support rod 36, as shown in FIG. 2, and the foregoing sequence of operations is repeated to form and mount another support member at a predetermined point on the filament.

It will be appreciated from the foregoing that the objects of the invention have been achieved insofar as a method and apparatus for simultaneously forming a wire support member and attaching it to a coiled filament have been provided. Since the configuration and diameter of the wire supports are controlled by the mandrel, the supports are very uniform and the filament is positioned within the envelope with greater precision than heretofore. Moreover, since the support-forming and anchoring ope-rations are performed simultaneously by a relatively simple method and apparatus, this phase of the lamp assembly operation can be performed in a very efiicient manner, even by unskilled labor.

While a specific embodiment of the aforesaid method and apparatus have been illustrated and described, it will be appreciated that various structural and procedural changes can be made without departing from the spirit and scope of this invent-ion. For example, it will be obvious that supports of non-circular and partly closed configuration can very readily be made simply by changing the shape of the mandrel and manner of trimming the ends of the wire.

I claim as my invention: 1. The method of forming and mounting a wire support member on an elongated incandescible filament comprising,

immobilizing at least that portion of the filament to which the support member is to be attached,

positioning a length of wire that is substantially straight and longer than that required for the support member transverse and tangent to said filament so that the latter contacts an intermediate portion of said length of wire,

wrapping a portion of said wire located adjacent to and on one side of said filament tightly around the latter and simultaneously bending the corresponding portion of said wire located on the other side of said filament into an arcuate loop to thereby form the intermediate portion of said length of wire into a support member of predetermined curvature and size that is disposed and anchored in encircling spaced-apart relationship :with said filament, and then trimming the ends of the formed support member to remove the excess end sections of said length of wire. 2. The method iof forming and mounting a support member of refactory metal wire on an elongated coil filament comprising,

holding rigid at least that portion of the filament to which the support member is to be attached,

positioning a length of refactory metal wire that is substantially straight and longer than that required for the support member along a predetermined axis that is substantially normal and tangent to the held portion of said filament so that the latter contacts the length of wire at a point closer to one end than the other,

wrapping the portion of the shorter segment of said length of wire that is located adjacent to and disposed on one side of said filament tightly around the latter and simultaneously bending the corresponding portion of the larger segment of said wire disposed on the other side of said filament into a loop of predetermined curvature and size so as to form the intermediate portion of said length of wire into a support member that is anchored to and disposed in encircling spaced apart relationship with said filament, and then severing the excess end segments of said length of wire from the ends of the formed support member.

3. The method of forming and mounting a support member of refractory metal wire on a linear coiled filament comprising,

inserting a rod through said filament to rigidity it, disposing the rigidified filament on a predetermined axis, positioning a predetermined length of refractory metal wire that is substantially straight and longer than that required for the support member along a predetermined axis that is substantially normal and tangent to the filament so that the -latter contacts said length of wire at a point closer to one end than the other,

bending the longer segment of said wire length into a closed loop of predetermined configuration and size and simultaneously winding the shorter segment disposed on the other side of said filament tightly around said filament first at a predetermined pitch angle and then at a reverse pitch angle so as to form at least a pair of cross-wound turns that lock the formed support member to said filament, and then severing the excess end portions of said wire length from the ends of the formed support member.

4. The method of forming and mounting a support member of resilient refractory metal wire on an elongated coiled filament comprising,

holding said filament so that at least that portion thereof to which the support member is to be attached is rigidified and extends along a predetermined axis,

pulling the end of a spool of resilient refractory metal wire over the foresaid portion of the filament along a predetermined path that is transverse and tangent thereto until a predetermined length of wire has been pulled beyond said filament,

maintaining the unspooled segment of wire under tension,

winding the portion of said wire segment that is located adjacent to and on one side of said filament tightly around the latter and simultaneously bending the corresponding portion of said wire segment located on the other side of said filament into a substantially circular helix of approximately two turns that is larger by a predetermined amount than the diameter of said filament and is offset from the filament axis toward the spool of said wire,

serving said wire segment proximate the end of the last turn of said helix so that the turns of said helix relax and spring back to form an enlarged circular helix that is substantially coaxial with said filament and has a protruding arcuate tail,

severing said tail from the enlarged helix, and then severing the excess portion of the wire segment from the opposite end of the formed helical support memher.

5. Apparatus for forming an arcuate support member from a substantially straight piece of Wire and simultaneously mounting said member on an elongated filament comp-rising,

means for holding the filament stationary along a first axis,

a mandrel having an aperture therethrough and an end face with a re-ent-rant slot that extends from the periphery of said mandrel to said aperture along a line substantially tangent to said aperture, said aperture being dimensioned to freely receive a filament located on said first axis,

means rotatably supporting said mandrel in a position such that said aperture is substantially coincident with said first axis,

means for rotating said mandrel about said first axis,

and

means located adjacent said first axis and the end face of said mandrel for guiding the end of a length of wire into the re-entrant slot and over a filament disposed in said mandrel along a second axis that is transverse to the first axis and tangent to said filament.

6. Apparatus for forming an arcuate support from a substantially straight piece of wire and simultaneously attaching said support to an elongated filament comprismeans for holding a filament in substantially coincident relationship with a first axis,

a mandrel of gene-rally cylindrical configuration having an aperture therethrough adapted to freely receive a filament loaded in said holding means,

said mandrel having an end face with a re-entrant slot 3 that extends from the periphery of said mandrel to said aperture along a line substantially tangent to said aperture,

a standard rotatably supporting said mandrel in a position such that said aperture is substantially concident with said first axis,

means comprising a pair of gears and a drive shaft for rotating said mandrel about said first axis,

a spool for holding a supply of wire positioned adjacent to and located in a plane transverse to said first axis, and

an apertured guide member disposed between said first axis and said spool for guiding wire from said spool over a filament loaded in said apparatus along a second axis that is substantially normal to said first axis and tangent to said filament.

7. Apparatus for forming an arcuate support member from a substantially straight piece of resilient relatively stiff wire and simultaneously mounting said member on an elongated coil filament comprising,

a base,

a pair of uprights on said base,

a chuck mounted on each of said uprights and disposed toward one another along a predetermined axis,

a rigid rod releasably clamped in said chucks and adapted to support an elongated coiled filament on said predetermined axis,

a standard attached to said base between said chucks an intersecting said predetermined axis,

an elongated die member rotatably supported by said standard along said predetermined axis and terminated at one end by a generally cylindrical mandrel having a flat end face,

said die member and mandrel having an aperture therethrough aligned with said predetermined axis and adapted to freely receive a filament mounted on said support rod,

the end face of said mandrel having a re-entrant slot therein that extends from its periphery to said aperture and is tangent thereto,

gear means rotatably supported by said standard and adapted when actuated to rotate said die member and mandrel about said predetermined axis,

a drive shaft coupled to said gear means and rotatably supported by an upright carried by said base,

means for controllably rotating said drive shaft, a spool rotatably supported by said base at a location behind and in line with said mandrel and disposed in a plane substantially normal thereto and to said predetermined axis, and

a guide member attached to said standard and disposed between said mandrel and spool and having an aperture therein that is oriented to guide the end of a supply of wire wound on said spool into the slot on the end face of said mandrel and into tangential engagement with a filament on said support rod along a path that is substantially normal to said predetermined axis.

8. Apparatus for forming an arcuate support member from a substantially straight piece of resilient relatively stiff wire and simultaneously mounting said member on an elongated coiled filament as set forth in claim 7 wherein,

said mandrel is eccentric with respect to the aperture therethrough,

said re-entrant slot extends from a point on the periphery of said mandrel furthest removed from said aperture and tapers toward the latter, and

the length of said support rod is such that -a filament loaded thereon can he slipped a predetermined distance therealong to permit wire supports to be formed and attached to said filament at preselected points.

(References on following page) References Cited by the Examiner UNITED STATES PATENTS Livingston 140-92.1 Clawson 140-122 Allen 140-122 Koenig 140--71.6 Foote 313274 Fitzpatrick 14071.5

3/1964 Schade 140-715 2/ 1965 Levand 313-274 7/ 1965 Blenvenue et a1 14071.5

FOREIGN PATENTS 4/1926 France.

CHARLES W. LANHAM, Primary Examiner.

W. H. I UST, Assistant Examiner. 

1. THE METHOD OF FORMING AND MOUNTING A WIRE SUPPORT MEMBER ON AN ELONGATED INCANDESCIBLE FILAMENT COMPRISING, IMMOBILIZING AT LEAST THAT PORTION OF THE FILAMENT TO WHICH THE SUPPORT MEMBER IS TO BE ATTACHED, POSITIONING A LENGTH OF WIRE THAT IS SUBSTANTIALLY STRAIGHT AND LONGER THAN THAT REQUIRED FOR THE SUPPORT MEMBER TRANSVERSE AND TANGENT TO SAID FILAMENT SO THAT THE LATTER CONTACTS AN INTERMEDIATE PORTION OF SAID LENGTH OF WIRE, WRAPPING A PORTION OF SAID WIRE LOCATED ADJACENT TO AND ON ONE SIDE OF SAID FILAMENT TIGHTLY AROUND THE LATTER AND SIMULTANEOUSLY BENDING THE CORRESPONDING PORTION OF SAID WIRE LOCATED ON THE OTHER SIDE OF SAID FILAMENT INTO AN ARCUATE LOOP TO THEREBY FORM THE INTERMEDIATE PORTION OF SAID LENGTH OF WIRE INTO A SUPPORT MEMBER OF PREDETERMINED CURVATURE AND SIZE THAT IS DISPOSED AND ANCHORED IN ENCIRCLING SPACED-APART RELATIONSHIP WITH SAID FILAMENT, AND THEN TRIMMING THE ENDS OF THE FORMED SUPPORT MEMBER TO REMOVE THE EXCESS END SECTIONS OF SAID LENGTH OF WIRE. 